Process of bleaching.



UNITED STATES ALFRED E. JURY, or NEW YORK, N. Y.,

lit/u tree Moron outta i PATENT OFFICE.

ASSIGNOR TO NATIONAL INDIA RUBBER COMPANY, A CORPORATION OF RHODE- ISLAND.

PROCESS OF BLEACHING.

No Drawing.

To all whom it may concern x Be it known that I, ALFRED E. JURY, a citizen of the United States, residing at New York, county of New York, and State of New York, have invented certain new and useful Improvements in Processes of Bleaching, of which the following is a full, clear, and exactdescription.

This invention relates to methods of bleaching textile materials and has for an object the prevention of the deleterious ac tion of the acids which are used in certain stages of the bleaching process, andwhich by the methods heretofore .used have not been entirely removed from the fabric. The

deleterious action above mentioned is particularly noticeable in fabrics of a close weave which are, at some time subsequent to the bleaching, subjected to relatively high heats. The steps of my process which actually perform the bleaching action are .the same as those ordinarily used, but for the sake of clearness I will outline the entire preferred treatment to which the goods are subjected. I

The" material is placed in a receptacle known as a keir and there boiled in a solution of caustic soda of about 3 Twaddell. This first boiling is for the purpose of cleaning thestock of any waxes or other foreign matter which may be present, and in most instances requires about twelve hours. Upon completion of the above boiling, the material is taken from the keir and washed in cold water by means of the ordinary washing machine and then subjected to the action of a solution of acid, either sulfuric, or a mixture of sulfuric and hydrochloric, of about 2 Twaddell. To permit the acid solution to produce-the proper action on the goods, they are allowed to lie saturated for approximately half an hour, after which they are again washed in cold Water.

The treatment thus far outlined is to re move any foreign substances present in the material, and puts it in proper condition for the application of the bleaching agent to which it is preferably-next subjected.

After the above mentioned washing, the

material is run through a bath of chloridexample as calcium hypochlorite which re- Serial No. 83,548.

eearcu noun;

mains in the material after the bleaching action has been completed is highly injurious, the goods being treated are run through a solution of inorganic acid (preferably sulfuric or sulfurous) and allowed to steep about an hour, after which they are again washed in cold waterf The acid solution last mentioned acts to neutralize the calcium hypochlgriteavhich remains in the material *aiftrfthe bleaching.

The procedure just outlined is the usual one and is not claimed as new. However, in the case of textiles which are to be used for certain purposes, it has been' found that the cold water washing does not effectively remove the acids with which they have been treated, and the presentinvention is for the purpose of neutralizing any which may still remain therein, and which produce decidedly harmful effects on the fabric. Particularly is this deleterious action of the remaining acid noticeable in the case of material which is subsequently subjected to high heat, in which case the goods are often tendered more than 25%. I carry out the neutralization of the acid'in the goods by subjecting them, immediately the last mentioned washing has been completed, to a hot solution of any suitable neutralizing agent, that which I have found most efficacious consisting of some such alkali as ammonia, borax, or sodium carbonate. Any other agent capable of neutralizing the acid is equally suitable and those enumerated are mentioned merely by way of example. I have found alkali in the proportion, about three per cent. of the Weight of the fabric being treated, produces excellent results. It is preferable that the alkali solution be hot since otherwise, especially in the case of a tightly woven fabr c, the penetration into the mesh is not comlete, and all the acid therein is not reached. nce it has penetrated, the alkali reacts with the acid in the mesh to form a neutral salt, which is washed out=in either hot or cold water. In case any traces of the salt remain in the goods however, they have no harmful ,efiect upon the material.

In order to assure com lete neutralization of all the inorganic aci s remaining in the goods after the cold water washing, I contemplate, in certain instances, forming the neutralizing bath of a concentration such that the proportion of alkali therein is considerably greater than in the case mentloned above. In this way, positive removal of all traces of acid is assured, the relative quantity of alkali being purposely made much greater than is necessary to neutralize the acid. This, however, leaves a considerable amount of free alkali in the material which, were it permitted to remain, would have a deleterious effect on the fabric, much the same as that of free inorganic acid, so an additional step to neutralize the alkali is necessary. This I accomplish by the application of a volatile organic acid which acts to neutralize the alkali, but which has no deleterious effect on the fabric, as does the inorganic acid to the action of which the goods were previously exposed.

While I have for the most part used acetic acid, any volatile organic acid is satisfactory for the purpose of neutralizing the alkali, and I do not wish to limit myself to any particular one.

agent, to a solution of an inorganic acid, to

the action of an alkali solution whereby any acid remaining in the material is neutralized, and finally neutralizing any excess of the alkali by the action of a volatile organic acid.

Signed at New York city, county of New York, State of New York, this 10th day of March, 1916.

y ALFRED E. JURY. 

